Blends of polycarbonate resins and polyester resins are known in the art. For example, U.S. Pat. No. 3,218,372 discloses blends of polycarbonates and polyalkylene terephthalates, and U.S. Pat. No. 4,125,572 discloses blends of polycarbonates, poly(1,4-butylene terephthalate) and a copolyester of an aliphatic or cycloaliphatic diol and a mixture of terephthalic and isophthalic acids. These polycarbonate/polyester blends exhibit many excellent properties which render them useful as films, fibers, and molded articles. They exhibit, for example, better ductility than neat polyesters and better processability than neat polycarbonates. Many of these blends, however, have a tendency to discolor or yellow. It would be very advantageous if blends of polycarbonate/polyester resins which have a tendency to yellow could be provided which possessed improved color properties, i.e., reduced yellowing.
It has been discovered that color formation in those polycarbonate/polyester resin blends which tend to discolor can be reduced by adding thereto a minor amount of a mixture of at least one polyol and at least one epoxide.